Hyperossification in miniaturized Toadlets of the genus Brachycephalus (Amphibia: Anura: Brachycephalidae): Microscopic structure and macroscopic patterns of variation

Species of the genus Brachycephalus, have a snout-vent length of less than 18 mm and are believed to have evolved through miniaturization. Brachycephalus ephippium, is particularly interesting; because its entire skull is hyperossified, and the presacral vertebrae and transverse processes are covered by a dorsal shield. We demonstrate in this paper that, at the macroscopic level, a completely hyperossified skull and dorsal shield occur only in B. ephippium, but not in B. ferruginus, B. izechsohni, B. pernix, B. pombali, B. brunneus, B. didactylus, and B. hermogenesi. An intermediate condition, in which the skull is hyperossified but a dorsal shield is absent, occurs in B. vertebralis, B. nodoterga, B. pitanga, and B. alipioi. The microscopic structure of hyperossification was examined in skulls of B. ephippium and B. pitanga, revealing a complex organization involving the presence of Sharpey fibers, which in humans are characteristic of periodontal connections.

Computed tomography with monochromatic bremsstrahlung radiation

The use of filters with appropriate thickness of different elements produces a method to quasi-monochromatize X-ray beams. In the present study the filters were produced in a boric acid matrix, using the elements Mo, Sb, Cs, Ce and Gd. The thickness of the filters varied from 50 to 300 microm for a high voltage tube operating from 30 to 70 kVp. The parameters analyzed were the beam resolution, measured by its FWHM as a function of filter thickness, and the reduction of beam intensity. The results show a comparison between conventional tomographies obtained with different filters and application in the technique of differential tomography, with double energy for identification of elements such as Zr, Nd, Ba and Sm.

Computed tomography: an evaluation of the effect of adding polymer SBS to asphaltic mixtures used in paving

This work applies the Computed Tomography (CT) technique to the study of asphaltic mixtures to which polymer has been added. An evaluation has been made of the effect of adding Brazilian produced polymer SBS (styrene-butadiene-styrene), to the asphaltic mixtures used in paving. Laboratory mechanical tests and non-destructive testing (NDT) of cylindrical specimens have been made. Three mixtures were prepared for the purpose of this study, all containing 5.4% of asphalt RASF (propane deashalting). One of the mixtures contained no polymer, while the other two were made with 7 and 5% of the SBS polymer. Investigations of Brazilian pavements have shown that cracking is the most important defect due to fatigue in the asphaltic contained overlay. Preliminary results of mechanical tests show that the polymer additive favorably enhances performance of the mixtures. It may be noted that adding polymer SBS to the asphaltic mixture used in paving increases the percentage void. Crack growth in specimens of asphaltic mixtures to which polymer has been added displays the same behaviors as that in specimens in which polymer has not been added.

Identification and dose determination using ESR measurements in the flesh of irradiated vegetable products

The international commerce of vegetable products is often dependent on the quarantine protections that are imposed by the importing countries because of the fear of contamination by fruit flies. The use of ionizing radiation as a treatment for these products can be used to remove this problem and a real proof of irradiation can contribute to the implementation of the international commerce. ESR measurement on the pulp of vegetable products can be used as a proof of irradiation using the species introduced in cellulose that are found uniquely in irradiated products. The stability of these species are compatible with the life of the products analyzed. The pulp signal intensity is sufficient to identify products irradiated with doses as low as 100 Gy for some fruits.